Art of manufacturing paraffin



May 27, 1930. C. A. WARD ART OF MANUFACTURING PARAFFIN Filed Nov. 20, 1925 Clarence A )Vard RNUEEQUN hvmmuQ Nam. 3m

"$50 mag-han NvQS HNNNDQ 95km A Patented" May 27, 1930 UNITED STATES PATENT OFFICE CLARENCE A. WARD, OF LINDEN, NEW JERSEY, ASSIGNOR TO STANDARD OIL DE- VELOPMENT COMPANY, A CORPORATION OF DELAWARE ART OF MANUFACTURING PARAFFIN Application filed November 20, 1925. Serial No. 70,413.

The present invention is directed to the art of treating hydrocarbon oils. The invention is directed more particularly to an improved process of obtaining paratfin as well as increased yields of other valuable prod ucts from hydrocarbons, as will be readily understood from the following description.

The drawing is a semi-diagrammatic view in elevation of an apparatus suitable for carrying out my invention and illustrates the flow of material.

Parafiin of commerce for a long time has been manufactured by the well-known process wherein a paraflin-containing distillate of desirable characteristics is first chilled to a point suflicient to separate out by solidification substantially all of the paraflin contained therein. The chilled distillate is then passed through the parafiin presses whereby a substantial quantity of the paraflin content, admixed with a certain proportion of oil, is separated from the main bulk of oil present.

The material so separated, which is termed a slack wax, is usually treated with acid for the removal of impurities and for improving the color of the product, and is then sweated to remove the liquid oil present, whereby a crude scale wax is obtained as a residuum. The sweating process is usually carried out by placing the solidified material, that is the slack wax, in an enclosed chamber, the temperature of which can be regulated as desired. The temperature of the wax is then raised Very slowly, whereby the more liquid portions of the wax sweat out and are withdrawn from the compartment. As the process continues, the wax content of the liquid removed increases until toward the end of the operation it has practically the same composition as the original stock charged to the sweaters. The first runnings, or the more liquid fractions obtained as described and which contain approximately of wax, are termed foots oil.

A foots oil as ordinarily obtained contains appreciable proportions of paraffin which can be separated therefrom by proper treatment. Normal operating practice as ordinarily carried out has long required that the foots oil be recycled with acertain amount of fresh paraffin distillate and again put throughthe process as described above. The foots oil, however, ordinarily contains a much greater proportion of paraffin than does the paraffin distillate, so that the amount of press space required for pressing a given volume of foots oil is very much greater than is required for pressing a corresponding volume of the fresh paraflin distillate. The use of an excessive amount of press capacity for handling a comparatively small volume of foots oil is a serious problem to refiners having a large volume of paraffin distillate to handle, particularly where the available press capacity is at all, limited. Although it has heretofore been considered that the recirculation of a foots oil was more or less essential for the satisfactory pressing of a fresh paratfin distillate, I have observed that this is not necessarily the case, as is shown hereinafter, especially when us1ng a paraffin distillate which in the course of its manufacture has been subjected to an eflicient rectification step during its separation from lighter and heavier ends.

The various advantages as set forth below can, as I have found, be realized by concentrating the foots oil from the sweating process by removing by distillation means approximately 40% by volume comprising the lighter portions of the oil, whereupon the 60% residuum will not need to be returned to parafiin distillate to be rechilled and repressed as in the ordinary procedure as outlined above, but can be sweated satisfactorily, whereby substantially complete separation of a paraflin of high quality follows. Although the distillation step mentioned may be carried out under a vacuum if desired, I have found that satisfactory results are realized by reducing the foots oil by means offire and steam, since all that is necessary is to avoid the possibility of substantial cracking of the stock under treatment.

Asan example of my invention, a sample of foots oil containing approximately 33.2% of paraflin, as indicated by the Holde method of determining this constituent, was distilled by fire and steam to approximately 60% bottoms while maintaining the temperature of the oil below 600 F. during the entire period .of heat treatment. The overhead distillate directly, thereby yielding 34.2% of a crude scale wax having a melting point in this case of 124 F. The crude scale wax so obtainedwasthen treated in the usual manner and 3 finished paraffin of high quality prouce 1 As another example, a sample of a foots' 'oil containing 29.6% paraiiimvas shown by the Holde method, was distilled approxi inately to a 60% bottoms by means of fire and steam at temperatures below 600 F. This residuum, asin the example shown above, was sweated directly, and after sweating-yielded 27 .4% of a crude scale wax having a melting point of 12:2.7 F. This product i also yielded a paraflin of commercial value when finishedin the usual manner.

The extent to which, the foots oil is re- I duced by distillation in the manner set forth above depends, of course, upon its paraflin content, but I have found if such an oil be reducedto a bottom or residuum possessing an oil content of approximately and Which'residuum solidifies more or less completely at approximately 100 F., the paratfin can be removed readily therefrom by direct sweating without preliminary chilling and repressing the material. The importance of this method of handling the foots oil may .be'reaIiZed when it is considered that by treating in the manner as set forth, a foots oil'having a paraflin content of 30% and thereby eliminating the necessity of repress- 7 ing this material, there is released sufficient press capacity to accommodate five times its volume of a paraifin distillate containing about 6% of paraflin. In other words, -ap-, proximately five times the pressing capacity is required for pressing a foots oil as is required for pressing the same volume of a fresh paraflin distillate. This excessive use of press capacity can be avoided by treating a foots oil in the manner as set forth.

Referring to the drawing reference character 1 designates a tank containing parafiin or wax distillate which is ke t liquid by steam coil 2. The oil is forced un er high pressure by pump 3 through line 4 to a heat exchanger 5 and then to a chiller6 which is cooled by brine. Brine circulation systemis not shown since it is well known in'the art. Chilled oil-3 and wax'solidified by "cooling then pass to wax press 7 and waxis'filtered from the bulk tions containing substantially moret of the oil which then flows through heat exchanger 5 and to storage (not shown).

, Wax is taken from the presses and put in a steam jacketed agitator 8 for acid and other f treatment as is well known and which forms no part of the present invention. The puri-.

fied wax now in a molten state is pumped toa heated feed tank 9 and thence to sweater 9 by a line 10. The sweater is a well known piece of refinery equipment and need not be described. 7

Wax is solidified'in layers in the sweater which is provided with pans 11 below each layer of solid wax which is indicated by 12. I

The temperature isthen slowly raised by steam coils (not shown) and the foots oil running down into pans 11 is'withdrawn by a pipe 13 andpumped to a still-14. The oil contains wax and the line 13 may be heated Still 14 is shown.

to prevent solidification.

as operating at normal atmospheric pressure with a steam spray 15 but a vacuum still may;

be used. Distillate is collected and condensed I in condenser 16 and pumped to storage (note) I a0 The unvaporlzed portion of residuum 1s,

shown) withdrawn from the still and pumped through line 17 to sweater feed tank 9 and is then recycled through the sweating process.

- Operation of the sweater is a batch method and foots oil is first collected. After all of the foots oil has been removed from thel; sweater intermedlate wax 1S melted andgis':

1. Intermediate wax collected in a tank 18. is customarily resweated. Paraflin wax substantially free of oil now remains in the sweater and is finally melted and collected in tank 19. I

Although I have shown the reduced foots oil returned to sweater 9 and mixed with fresh slack wax, it may be resweated alonein a separate sweater as is apparent. a g

Although I have described my process as applicable to the treatment of a foots-oil,} it& is tobe understood that any hydrocarbon fraction containing a relatively high porpor tion of paraffin, for example 20% or higher,

may likewise be treated. In the-case'offmo '1 tions containing less than 30%kpar'aflinythe reduction with fire and steamwould be carried out in a manner to obtain-falargerprcentage of overhead dist-illate fthan-itl fort-11in the examples given,

a ea

paraffin the reduction by heaewoaid, not b e.

carried so far but alarger proportion'fof-residuum would be left for thesweating'treab,

ment. t While in describing my invention I have understood that these are l-i'l'lustrative only and not limitative. Nor'uis my invention to.

be-=understood' as depending upon the ac'cu v racy of any theory or, reason suggest'ed'to ex;-

referred to certain.speoific details,it will be plain the advantageous result. On the contrary, the invention is to be regarded as limited only as defined in the following claims, in which it is my intention to claim all novelty inherent in my process as broadly as the prior art permits.

lVhat I claim is:

1. The process of obtaining paraflin from a petroleum distillate containing more than 20% of paraffin comprising redistilling without substantial cracking whereby a residuum is obtained substantially solid at approximately F cooling the residuum and sweating it to obtain paraffin.

2. The process of obtaining paraflin from a foots oil, which comprises separating the foot-s oil by distillation to approximately 600 F. into a volatile portion and a residuum, cooling and then sweating said residuum.

3. The process of obtaining parafiin from a foots oil, which comprises reducing said foots oil substantially to a 60% bottoms by means of distillation at a temperature below 600 toms.

4. The process of obtaining paraflin from a foots oil. which comprises reducing said foots oil by means of fire and steam substantially to a 60% bottoms cooling and then sweating said bottoms.

5. The process of obtaining parafiin from a petroleum distillate, which comprises concentrating said distillate at temperatures below the cracking temperature to a residuum, solid at room temperature, which can be sweated directly.

6. The process of obtaining paraflin from a petroleum distillate, which comprises concentrating said distillate at temperatures below the cracking temperature to a residuum containing approximately 50% of a paraflin, cooling and then directly sweating said residuum.

CLARENCE A. WARD.

F., cooling and then sweating said bot- 

